Expansion joint seal

ABSTRACT

An expansion joint seal for bridging and sealing an expansion space between structural members comprises a pair of elongated frame members, each of which is adapted to be secured rigidly to one of the structural members on either side of the joint, an elongated substantially rigid bridge member extending lengthwise of the joint and spanning the expansion space between the structural members, the lateral edges of the bridge member being spaced from the edges of the frame members, and a seal member of elastomeric material received between the bridge member and the edges of the respective frame members. The frame members and bridge member include companion surfaces disposed in substantially horizontal planes so that the frame members support the bridge member but are able to move toward and away from each other and relative to the bridge member. Generally C-shaped cavities are provided at, first, a portion of each frame member adjacent and above the horizontal supporting surface and, second, portions adjacent the lateral edges of the bridge member, the respective cavities of the frame members and bridge member facing each other across the space above the horizontal surfaces of the frame members. The elastomeric material extends into and is therefore captured and sealed within the C-shaped cavity on each frame member and on the bridge member. The inherent resiliency of the elastomeric material tends to hold the bridge member centered between the frame members and distends in accordance with relative movements of the frame members. A bond breaker medium is provided between the seal members and all underlying substantially horizontal surfaces of the frame member and bridge member and prevents any bonding between the seal members and such surfaces.

United States Patent McGeary et al.

[ EXPANSION JOINT SEAL [75] Inventors: Frank L. McGeary, Scotch Plains;

Patrick L. Zampetti, Cranford, both of NJ.

[73] Assignee: Construction Specialties, Inc.,

Cranford, NJ.

[22] Filed: Dec. 29, 1971 [21] Appl. No.: 213,684

[52] US. Cl. 404/69 [51] Int. Cl. E01c 11/04 [58] Field of Search 94/18, 18.2; 52/395,

[56] References Cited UNITED STATES PATENTS 3,183,626 5/1965 Schmitt 94/18 3,527,009 9 1970 Nyquist... 94/18 3,629,986 12/1971 Klittich 52/396 3,371,456 3/1968 Balzer et al 94/18 3,394,639 7/1968 Viehmann 94/18 Primary Examiner-Roy D. Frazier Assistant ExaminerThomas J. Holko Att0rneyGranville M. Brumbaugh et al.

[57] ABSTRACT An expansion joint seal for bridging and sealing an expansion space between structural members comprises a pair of elongated frame members, each of which is adapted to be secured rigidly to one of the structural members on either side of the joint, an elongated substantially rigid bridge member extending lengthwise of the joint and spanning the expansion space between the structural members, the lateral edges of the bridge member being spaced from the edges of the frame members, and a seal member of elastomeric material received between the bridge member and the edges of the respective frame members. The frame members and bridge member include companion surfaces disposed in substantially horizontal planes so that the frame members support the bridge member but are able to move toward and away from each other and relative to the bridge member. Generally C-shaped cavities are provided at, first, a portion of each frame member adjacent and above the horizontal supporting surface and, second, portions adjacent the lateral edges of the bridge member, the respective cavities of the frame members and bridge member facing each other across the space above the horizontal surfaces of the frame members. The elastomeric material extends into and is therefore captured and sealed within the C-shaped cavity on each frame member and on the bridge member. The inherent resiliency of the elastomeric material tends to hold the bridge member centered between the frame members and distends in accordance with relative movements of the frame members. A bond breaker medium is provided between the seal members and all underlying substantially horizontal surfaces of the frame member and bridge member and prevents any bonding between the seal members and such surfaces.

EXPANSION JOINT SEAL BACKGROUND OF THE INVENTION This invention relates to expansion joint seals for bridging and sealing an elongated expansion space between adjacent horizontal members of a building structure.

It is common practice in the construction of large buildings to provide expansion spaces between portions of the structure that allow for relative expansion and contraction of such portions or for other forms of relative movement between the portions, such as deflection due to wind load or other loading conditions. In general, such expansion spaces are located at extremities of structural units of a building and are constituted by parallel, spaced-apart structural members of two adjacent units. Inasmuch as expansion spaces may in some instances be located at places other than between structural members (structural" in the sense of providing primary load carrying ability in the structure), the term structural members are used herein is used in its broadest sense as applying to any members in a building structure and, therefore, includes not only structural beams, but floor panels, roof panels and similar building elements.

Many forms of covers or bridges for filling the space between adjacent structural members at an expansion joint have been proposed and used heretofore. Some forms of closures for expansion joints in building construction provide only limited load carrying ability and are intended primarily simply to fill the space for esthetic or utility reasons other than load carrying. For example, some joints are caulked or filled with a material that renders the joint air and water tight.

Although a joint according to the present invention may be used in almost any expansion space for the relatively limited purpose of sealing the space, the expansion joint seal, according to the present invention, is intended primarily for load-carrying uses. In general, load-carrying types of expansion joint seals or bridges include a bridge member extending across the joint and supported on frame members secured to the structural members on either side of the expansion space so that loads imposed on the bridge member are carried across the joint and into the building members on either side of the expansion space.

Applicants assignee has for some years manufactured and sold several forms of expansion joint covers or seals including some types that provide substantial load-carrying ability by virtue of including a substantially rigid bridge member extending across the joint. One such form of expansion joint seal and cover is described in U.S. Pat. No. 3,394,639 granted July 30, 1968, entitled Expansion Joint, and owned by applicants assignee. The expansion joint described in that patent comprises frame members secured to the building members on either side of the expansion space, a bridge member spanning the space between and sup ported on horizontal surfaces of the frame members, and preformed elastomeric members received in spaces in between side flanges formed on the respective frame members and the side edges of the bridge member. The preformed elastomeric members are compressed in the spaces so that they expand upon movement of the structural members away from each other, and they are constructed so that they are readily compressed upon movement of the structural members toward each other.

Although the expansion joint bridge of U.S. Pat. No. 3,394,639 has proved very successful in service, occasional problems have arisen insofar as providing an effective water seal. It is possible for fine particles of dirt to work down between the elastomeric sealing members and provide enough of a gap at the interfaces between the sealing members and the other members of the joint to allow water leakage. While the problem has generally been negligible or non-existent when such joints are used in interior or covered areas of a building structure, the absence of a positive seal in the joint construction can be a significant problem when the joint is used in open or exposed areas, such as in a roof, or in other areas where there may be substantial exposure to dirt and water, for example, in a parking garage.

SUMMARY OF THE INVENTION There is provided, in accordance with the present invention, an improved expansion joint seal of the type used to bridge and seal an expansion space between structural members. The expansion joint seal of the invention includes a load-carrying bridge member extending across the joint and highly effective seal members of an expandable elastomeric material that are bonded and captured within cavities formed in the respective members and insure a durable and tight seal at the joint.

More particularly, an expansion joint seal, according to the invention, comprises a pair of elongated frame members, each of which is arranged to be secured rigidly to one of the structural members adjacent the expansion space and extends lengthwise of the structural members. Each frame member is of uniform crosssection along its length and includes, in cross-section, a top marginal portion formed with a cavity that has an opening facing generally inwardly toward the expansion space, the interior of the cavity having, in crosssection, a greater dimension than the cross-sectional dimension across the opening. Each frame member also has a horizontal base portion adjacent the cavity portion, the base portions of the frame members having surfaces that are substantially co-planar when the members are installed in the joint. A substantially rigid, elongated bridge member extends lengthwise of the joint and across the expansion space and has surfaces that engage and are supported by the horizontal surfaces of the frame members. The lateral edges of the bridge member are spaced from the edge of each horizontal surface of the respective frame members so that relative sliding movement of the frame members toward and away from each other and relative to the bridge member is afforded. The side edges of the bridge member are also formed with cavities, the cavities facing generally outwardly from the space and being located generally opposite the cavities in the respective frame members. A unitary body of an elastic material is received in each space between the cavity portion of the frame member and the cavity portion of the bridge member, each body of elastomeric material filling the space and being received, and bonded and sealed, within the cavities firmly to be interconnected between the frame member and the bridge member and provide a highly effective water and dirt seal at the joint. The elastomeric material, nonetheless, distorts in shape and dimension upon relative movement of the frame members to accommodate such movement.

The seal members are preferably formed in situ by pouring an appropriate elastomeric material in liquid or semi-liquid form into the spaces between the edges of the bridge members and the edges of the frame members. The in-place formation of the sealing members affords an essentially permanent bonding of the sealing members to the bridge member and to the frame members.

An important feature of the invention is the provision of a bond breaker medium between substantially all horizontal surfaces of the frame members and the bridge member in zones thereof occupied by the elastomeric material. The bond breaker medium may be a flexible, thin strip of a material that is non-adherent to either the material of the frame member or the elastomeric material or both or a fluid coating of a material that inhibits bond formation between the elastomeric material and the material of the frame member and is provided between all generally horizontal interfaces between the elastomeric material, on the one hand, and the frame and bridge members, on the other hand. The inhibition of a bond at the horizontal interfaces ensures distortion of the elastomeric sealing members relatively uniformly throughout their cross-section without the inhibiting effect of a bond between the elastomeric members and the other components of the seal of the joint structure at such horizontal interfaces.

As a further preferred feature of providing a highly effective water seal at the expansion joint, each frame member of the joint seal has a slot that receives an edge portion of a liquid-impermeable membrane that is built into the building structure. The membrane is held in place in the slot by a compressible retainer band extending continuously along the slot and captured within the slot so that it clamps and seals the membrane continuously along the edge of the frame member and ensures against leakage between the structural member and the frame member, since the frame member is sealed to the membrane and blocks the passage of any water trapped at the membrane.

The expansion joint seal of the invention provides important advantages. For one thing, it provides a loadcarrying ability by virtue of a rigid bridge member extending between and supported by the frame members, thus making the joint particularly suitable for buildings in which substantial loads will be imposed in areas across the joints. For example, the expansion joint seal is particularly useful for parking garages in which automobiles and other traffic will traverse the joint and will carry dirt and water over the joint. The sealing characteristics of the joint, insofar as it provides sealed and bonded elastomeric members and may also include the uniting of the joint frame with a membrane, make the joint also highly useful in exposed areas of a building, such as a roof. The bodies of elastomeric material mechanically unite the bridge member with the frame members to provide a unitary bridge structure extending across the joint between the frame members. The inherent elastomeric properties of the elastomeric material, coupled with substantially free movement of the bridge member relative to the frame members, provide a self-centering effect in that the bridge member will tend to occupy a center position at the joint; the greater the tendency of the bridge member to be located off center, relative to the two frame members, the greater is the tendency for centering, because the inherent elastomeric properties of the elastomeric seal members will result in an unequal force application by one of the other bodies of elastomeric material in the joint when the bridge member is off center, and this force imbalance will tend to shift the bridge member to a centered position. For example, when the structural members, and therefore the frame members, are more widely spaced than the neutral or normal position, both seal members are stretched and under tension. If the bridge member is not centered, the tension forces generated by the body of elastomeric material that is more greatly stretched will tend to pull the bridge member to the center position and balance the force distribution between the two elastomeric members. In addition to maintaining a balance of forces between the two elastomeric members, which will prevent either one from being overstressed in use, the balancing of forces and the centering effect on the bridge member assists in retaining the bridge member in proper supported relation on the frame members.

Inasmuch as the bridge member and the bodies of elastomeric material and the frame members tend to form a unit, by reason of the in situ formation of the bodies of elastomeric material, it is advantageous to construct the frame members in two parts, one part of which includes the cavities that receive the elastomeric bodies and the horizontal surfaces supporting the bridge member, and the other part being separate and permanently installed in the structural system. The first parts are appropriately secured to the permanent parts in a manner that permits them to be readily removed so that the entire bridge member and seal member assembly can be removed from the expansion space to permit access to the space.

DESCRIPTION OF THE DRAWINGS For a better understanding of the invention and of the advantages it provides, reference may be made to the following description of an exemplary embodiment, taken in conjunction with the accompanying drawing, which is an end view in cross-section taken at a representative point along the length of the embodiment and substantially perpendicular to the plane of the floor of the structure, portions of the structural members associated with the joint also being shown.

DESCRIPTION OF AN EXEMPLARY EMBODIMENT In the drawing, the reference numeral 10 designates an expansion space between opposed faces 12 and 14 of an elongated expansion joint between a pair of spaced-apart structural members 16 and 18. In the embodiment, the structural members are represented as reinforced concrete beams, but it will be understood by those skilled in the art that various members may be located on either side of an expansion space and that the embodiment and other forms of an expansion joint seal, in accordance with the invention, may be used in various structural environments.

The embodiment comprises a pair of elongated frame members 20L and 20R appropriately secured to the respective structural members 16 and 18 and extending lengthwise of the joint 10. Inasmuch as the frame members 20L and 20R are identical, only one needs to be described. Each frame member 20L or 20R is composed of two parts, a detachable part 22 and a permanently installed part 24, both parts being elongated members of uniform cross-section. Advantageously, they are extrusions from aluminum, brass or the like. The permanently installed part 24 includes, in crosssection, a body portion 26 formed with longitudinally spaced apart tapped holes 28 for receiving fasteners 30 by which the removable part 22 is secured to the permanent part 24. The permanent part 24 further includes, in cross-section, a laterally outwardly extending flange portion 32 through which fasteners 33 are inserted at appropriate spacing lengthwise of the joint to secure the permanent part 24 to the structural member 16 or 18. Although the fastener in the embodiment is a bolt and expansion anchor, other forms of fasteners, such as concrete anchors in concrete construction and various types of interconnection in other forms of structure, may be provided.

The permanent member 24 further includes, in crosssection, a verticalflange 34 that extends up to essentially finished floor grade and provides a grade level by which a final floor layer can be brought to proper level with the joint seal. The flange 34 also provides a companion engaging surface for the outermost extremity of the .removable frame member part 22.

Frequently, a building structure in which the expansion jointis used will have a water and vapor seal membrane 36 associated with it. To ensure a tight seal at the intersection between the structural member and the joint seal, the edge of the membrane 36 is brought up to the frame and secured to it by inserting the edge in a generally C-shaped slot 38 and anchoring it in place in the slot by inserting a locking rod 40 of a resilient elastomeric material. The elastomeric rod form of lock 40 not only mechanically secures the membrane in place to the frame member but ensures a good seal between the membrane and the frame member to prevent possible leakage from occurring at the intersection between the expansion joint seal structure and the adjacent portion of the building structure.

The removable part 22 of the frame includes a base portion 42 that presents a substantially horizontal surface of a width, in a direction transverse to the length of the joint, sufficient to provide for the desired amount of relative movement of the building structures. A pair of continuous parallel, spaced-apart legs 44 and 46 depend from the underside of the portion 42 and are supported on shims 47 (or directly on the surface of the structural member). Alternatively, the bottoms of the legs 44 and 46 may rest on a flange (not shown) extending inwardly from the base of the body portion 26 of the permanent part 24 of the frame to or near to the inner edge of the structural member 16 or 18. The inner end, relative to the expansion space, of the base portion 42 is formed with a small depending rib 48 and an overhanging lip 50 that define a small continuous slot that receives the upper end of a leg of a W-shaped spring 54 that holds a bridge member 56 down in place on the frame members 20L and 20R.

The removable part 22 of each frame further includes a body portion 60 that is formed, in crosssection, with a generally C-shaped, inwardly opening cavity 62. The dimension of the inside of the cavity is greater than the opening of the cavity so that a seal member 64 of an elastomeric material that is poured in place in the joint is received in the C-shaped cavity and is mechanically anchored and adhesively united and sealed within the cavity. The screws 30 by which the removable member 22 is secured to the permanent member 24 of each frame member extend through holes drilled and countersunk through the body portion 60 at appropriate spacing.

The two-part construction of each frame member is a preferred feature; a single frame member cna readily be provided of generally similar format. Moreover, various specific configurations for the frame member are, of course, possible and will be readily apparent to those skilled in the art.

The space across the expansion joint 10 between the frame members is bridged by a bridge member 56 that extends the entire length of the frame members and is dimensioned and shaped appropriately to be supported by the frame members and to carry vertical loads imposed upon it across the joint and into the frame members and thence into the structural members on either side of the joint. In this regard, the width of the bridge member 56 is such that at the position of greatest separation between the innermost edges of the frame members, which condition will obtain, of course, when the structural members of the building are at their widest separation, the bridge member remains supported by the base portions 42 of the frame members. In the em bodiment, the outer-most edges of the bridge member 56 are formed with outwardly projecting flange portions 61 that are part of the surface by which the bridge member is supported on the base portions 42 of the respective frame members. Each flange 61 may be of substantially greater width than shown to accommodate greater movements between the structural members. Similarly, the lateral dimensions of the horizontal surfaces of the frame members can be somewhat larger than the dimensions illustrated in the drawings.

Each side edge of the bridge member 56 is formed with a generally C-shaped cavity 63 which is shaped and dimensioned similarly to the corresponding cavities 62 in the frame member parts 22. The body 64 of elastomeric material extends into the cavities 63 to unite the bodies of elastomeric material by a mechanical interlock and by adhesion.

More particularly, the seal members 64 are formed of an elastomeric material that is poured in place with the members preassembled in the position they will occupy in the joint, as installed in the building, when the expansion space is at a neutral configuration, that is, at the nominal neutral design width of the expansion space 10. Various elastomeric materials, particularly various synthetic rubbers or other elastomeric polymers, may be used for the sealing members 64. Very good results are obtained with two-part polyurethane compounds. Although the sealing member 64 may be poured in the field on the job, it is advantageous, be cause of the advantages of providing controlled conditions and maintaining cleanliness in the joint parts, to factory-pour the seal members 64.

It is evident that the shape of the cavities 62 of the frame members and the cavities 63 of the bridge member provide a mechanical interlock between the sealing members. Advantageously, however, it is also desirable to provide an adhesive bonding between the seal members and the cavities, and various elastomeric materials having good bonding properties with aluminum or other metals from which the frame member and bridge member may be formed are available. Various known primer materials may be applied to the portions of the frame member and bridge member to enhance the bonds.

It is also evident that the sealing material would form a bond with the horizontal surface presented by the base portion 42 of each frame member and the essentially horizontal surface 58 of the outwardly projecting flange 61 of the bridge member 56. Inasmuch as such a bond would tend to impede a uniform distortion of the sealing material and might tend to create stress concentrations and possible failure conditions in the sealing material, it is an important feature of the invention to provide a bond breaker" medium at any potential interface between the seal member 64 and all horizontal or substantially horizontal surfaces of the bridge member and the frame member. Various forms of bond breaker medium, such as strips of flexible film material that are non-adherent to either the seal member or the frame or bridge members, or a coating of a release agent, such as a silicone release liquid, may be used. In the embodiment, the bond breaker medium is a strip 70 of a lightly adhesive tape having a silicone-treated backing, the adhesive side of the tape being applied to the flange 58 of the bridge member 56 and to the base portion 42 prior to pouring the sealing member 64. The tape offers the advantages of staying in place and ensuring against leakage during the pouring operation.

The bridge member is held in place on the frame members by a series of longitudinally spaced-apart W- shaped leaf-type springs 54 secured by bolts 72 to the bridge member. The center apex of the W-spring receives an elongated threaded fastener 74 that has lugs 76 projecting out through slots in the spring so that the fastener 74 is securely held on the spring 54, and the upper ends of the outermost free legs of the spring 54 are captured in the slots at the innermost ends of the frame members 22. The screw 72 is inserted through the bridge member 56 and tightened to draw the apex of the spring upwardly and hold the bridge member down on the frame members. The W-configuration of the springs affords relative inward and outward movement of the frame members.

in use, the structural members and frame members move toward and away from each other as the structural members 16 and 18 of the building move toward and away from each other. Upon relative inward movement of the frame members, the sealing members 64 are compressed and will distort to accommodate such compression. Should one or the other of the sealing members 64 tend to be compressed to a greater extent that the other, a correspondingly greater force resisting compression will be developed and will tend to shift the bridge member laterally toward the more lightly compressed sealing member. A similar effect occurs as the structural members move farther apart and place the sealing members in tension. Thus, the sealing members tend to hold the bridge member in centered relation between the frame members.

The mechanical interlocks between the sealing members and the respective frame members and the bridge member provide effective liquid and dirt seals between the several members at the joint. Such seals are further enhanced by providing an adhesive bond. Thus the joint provides highly effective sealing of the expansion space.

The expansion joint seals of the invention may be constructed in appropriate lengths or sections, and the sections united or joined at butt joints or corners. Usually, the adjacent ends of two sections are spaced apart to allow expansion and contraction lengthwise of the sections. The space can be filled and sealed by installing a bridging strip immediately under the endmost portions of the bridge members of adjacent sections, such bridging strips being supported on the laterally innermost ends of the frame members. The same elastomeric material as used for the sealing member 64 in the main expansion joint seals can be poured in place in the gap between the ends of butted or corner-to-corner sections. Accordingly, a butt or corner-to-corner joint between two sections of the expansion joint seals provides for longitudinal relative expansion and contraction of the joint structure, for load-carrying, and for effective sealing.

It is apparent that by removing the screws by which the bridge member is held down on the frame members, the bridge member can be removed by pulling it upwardly. However, this would result in destruction of the seal members. Accordingly, it is preferable to remove the screws by which the removable parts of the frame members are secured to the permanent parts. This permits the entire joint assembly, except for the permanent frame members, to be removed for access to the joint. This is entirely an optional feature but offers the significant advantage of permitting the joint cover to be removed and replaced, should it be neccssary to do so, without destruction.

In the embodiment, there are two sealing members 64, one on either side of the bridge member 56, and the top surface of the bridge member is at finished surface level. It will be apparent to those skilled in the art, however, that the bridge member may be recessed below the finished surface and that the sealing material may carry entirely across the top of the joint and over the bridge member. In such a case, a bond breaker is provided entirely across the span underneath all horizontal or substantially horizontal surfaces of the seal member.

The embodiment of the invention described above is intended to be merely exemplary, and those skilled in the art will be able to make numerous variations and modifications of it without departing from the spirit and scope of the invention. All such variations and modifications are intended to be included within the scope of the invention, as defined in the appended claims.

We claim:

1. An expansion joint seal for bridging and sealing an expansion space between structural members comprising a pair of elongated frame members, each of which is arranged to be secured rigidly to one of the structural members adjacent the space and to extend along the length of said members, each frame member being of uniform cross-section along its length and including in cross-section a portion defining a cavity having an opening facing generally inwardly toward the expansion space, the interior of the cavity having a greater cross-sectional dimension than the dimension across said opening, and each frame member including a base portion adjacent the cavity portion, the base portions of the members having surfaces that are substantially coplanar when the members are installed at the joint, and each frame member further including in crosssection a generally C"-shaped slot located along a marginal portion thereof remote from the expansion space; a substantially impermeable fluid membrane of flexible material disposed adjacent each frame member, each membrane having a portion received in said slot; a resilient retainer member received in the slot to hold the membrane in place; a substantially rigid elongated bridge member extending lengthwise of the joint, spanning the expansion space, having surfaces engaging the said coplanar surfaces of the frame members for relative sliding movement and having in cross-section a portion along each longer side edge defining a cavity that faces generally outward from the space and is generally opposite the cavity in a respective frame member, the side edges of the bridge member being spaced from the outer extremities, relative to the expansion space, of said frame membersurfaces and providing a zone between the bridge member and each frame member for substantial sliding movement of the bridge member relative to the frame members; and a unitary body of an elastomeric material received in each said zone and in the cavities of the respective frame and the bridge members, each said body filling said zone and being bonded and sealed to the cavities but being free of any substantial bond to said coplanar surface of the frame member.

2. An expansion joint seal according to claim 1 and further comprising a bond breaker medium between said coplanar surfaces and the respective body of elastomeric material to prevent the formation of a bond between the said coplanar surfaces and the body of elastomeric material.

3. An expansion joint seal according to claim 1 wherein the cavities are generally C-shaped in crosssection and provide a mechanical interlock with the body of elastomeric material received therein.

4. An expansion joint seal according to claim 1 and further comprising at least one retainer acting between the frame members and the bridge member for resiliently retaining the said surfaces of those members in engagement while affording relative sliding movement.

5. An expansion joint seal according to claim 1 wherein the elastomeric material received in each zone reacts to any lateral deformation of the material in the opposite zone causing movement of the bridge member and resists said deformation thus tending to hold the bridge member in a substantially centered position between the frame members.

6. An expansion joint seal for bridging and sealing an expansion space between structural members comprising a pair of elongated frame members, each of which is arranged to be secured rigidly to one of the structural members adjacent the space and to extend along the length of said members, each frame member being of uniform cross-section along its length and including in cross-section a portion defining a cavity having an opening facing generally inwardly toward the expansion space, the interior of the cavity having a greater cross-sectional dimension than the dimension across said opening, and each frame member including a base portion adjacent the cavity portion, the base portions of the members having surfaces that are substantially coplanar when the members are installed at the joint, and each frame member further including a first part that includes the cavity portion and base portion, and a separate second part to support the first part and arranged to be secured to the structural member; a substantially rigid elongated bridge member extending lengthwise of the joint, spanning the expansion space, having surfaces engaging the said coplanar surfaces of the frame members for relative sliding movement and having in cross-section a portion along each longer side edge defining a cavity that faces generally outward from the space and is generally opposite the cavity in a respective frame-member, the side edges of the bridge member being spaced from the outer extremities, relative to the expansion space, of said frame member surfaces and providing a zone between the bridge member and each frame member for substantial sliding movement of the bridge member relative to the frame members; a unitary body of an elastomeric material received in each said zone and in the cavities of the respective frame and the bridge members, each said body filling said zone and being bonded and sealed to the cavities but being free of any substantial bond to said coplanar surface of the frame member; and means positioned for access for detachably securing the first part of the frame member to the second part thereof such that an assembly that includes at least the first parts of the frame members, the bodies of elastomeric material and the bridge member is readily removable from and replaceable in the joint as a unit. 

1. An expansion joint seal for bridging and sealing an expansion space between structural members comprising a pair of elongated frame members, each of which is arranged to be secured rigidly to one of the structural members adjacent the space and to extend along the length of said members, each frame member being of uniform cross-section along its length and including in crosssection a portion defining a cavity having an opening facing generally inwardly toward the expansion space, the interior of the cavity having a greater cross-sectional dimension than the dimension across said opening, and each frame member including a base portion adjacent the cavity portion, the base portions of the members having surfaces that are substantially coplanar when the members are installed at the joint, and each frame member further including in cross-section a generally ''''C''''-shaped slot located along a marginal portion thereof remote from the expansion space; a substantially impermeable fluid membrane of flexible material disposed adjacent each frame member, each membrane having a portion received in said slot; a resilient retainer member received in the slot to hold the membrane in place; a substantially rigid elongated bridge member extending lengthwise of the joint, spanning the expansion space, having surfaces engaging the said coplanar surfaces of the frame members for relative sliding movement and having in cross-section a portion along each longer side edge defining a cavity that faces generally outward from the space and is generally opposite the cavity in a respective frame member, the side edges of the bridge member being spaced from the outer extremities, relative to the expansion space, of said frame membersurfaces and providing a zone between the bridge member and each frame member for substantial sliding movement of the bridge member relative to the frame members; and a unitary body of an elastomeric material received in each said zone and in the cavities of the respective frame and the bridge members, each said body filling said zone and being bonded and sealed to the cavities but being free of any substantial bond to said coplanar surface of the frame member.
 2. An expansion joint seal according to claim 1 and further comprising a bond breaker medium between said coplanar surfaces and the respective body of elastomeric material to prevent the formation of a bond between the said coplanar surfaces and the body of elastomeric material.
 3. An expansion joint seal according to claim 1 wherein the cavities are generally C-shaped in cross-section and provide a mechanical interlock with the body of elastomeric material received therein.
 4. An expansion joint seal according to claim 1 and further comprising at least one retainer acting between the frame members and the bridge member for resiliently retaining the said surfaces of those members in engagement while affording relative sliding movement.
 5. An expansion joint seal according to claim 1 wherein the elastomeric material received in each zone reacts to any lateral deformation of the material in the opposite zone causing movement of the bridge member and resists said deformation thus tending to hold the bridge member in a substantially centered position between the frame members.
 6. An expansion joint seal for bridging and sealing aN expansion space between structural members comprising a pair of elongated frame members, each of which is arranged to be secured rigidly to one of the structural members adjacent the space and to extend along the length of said members, each frame member being of uniform cross-section along its length and including in cross-section a portion defining a cavity having an opening facing generally inwardly toward the expansion space, the interior of the cavity having a greater cross-sectional dimension than the dimension across said opening, and each frame member including a base portion adjacent the cavity portion, the base portions of the members having surfaces that are substantially coplanar when the members are installed at the joint, and each frame member further including a first part that includes the cavity portion and base portion, and a separate second part to support the first part and arranged to be secured to the structural member; a substantially rigid elongated bridge member extending lengthwise of the joint, spanning the expansion space, having surfaces engaging the said coplanar surfaces of the frame members for relative sliding movement and having in cross-section a portion along each longer side edge defining a cavity that faces generally outward from the space and is generally opposite the cavity in a respective frame member, the side edges of the bridge member being spaced from the outer extremities, relative to the expansion space, of said frame member surfaces and providing a zone between the bridge member and each frame member for substantial sliding movement of the bridge member relative to the frame members; a unitary body of an elastomeric material received in each said zone and in the cavities of the respective frame and the bridge members, each said body filling said zone and being bonded and sealed to the cavities but being free of any substantial bond to said coplanar surface of the frame member; and means positioned for access for detachably securing the first part of the frame member to the second part thereof such that an assembly that includes at least the first parts of the frame members, the bodies of elastomeric material and the bridge member is readily removable from and replaceable in the joint as a unit. 